This is the nomenclature ....

\begin{center}
{\Large\bf Units}\\
This thesis uses English units to keep with North American
aerospace industry practice.  The following conversion factors are
provided to convert to S.I. units:\\ \vspace{12pt}
\begin{tabular}{cc}
  \hline
  % after \\: \hline or \cline{col1-col2} \cline{col3-col4} ...
  English Unit & S.I. Conversion \\
  \hline\hline
  in & 25.4 mm \\
  lbf & 4.45 N \\
  ksi & 6.89 MPa \\
  \hline
\end{tabular}
\end{center}
